Posted
by
samzenpuson Friday February 22, 2013 @12:34AM
from the we're-doomed dept.

Copper Nikus writes "An article at the BBC makes a shocking claim about mosquitoes. It appears some individual insects in the wild have developed the ability to ignore the very popular DEET repellent after a first exposure. From the article: 'To investigate why this might be happening, the researchers attached electrodes to the insects' antenna.
Dr Logan explained: "We were able to record the response of the receptors on the antenna to Deet, and what we found was the mosquitoes were no longer as sensitive to the chemical, so they weren't picking it up as well.
"There is something about being exposed to the chemical that first time that changes their olfactory system - changes their sense of smell - and their ability to smell Deet, which makes it less effective."'"

John Quiggin and Tim Lambert have written that "the most striking feature of the claim against Carson is the ease with which it can be refuted." DDT was never banned for anti-malarial use,[85] (its ban for agricultural use in the United States in 1972 did not apply outside the US or to anti-malaria spraying;[86] the international treaty that banned most uses of DDT and other organochlorine pesticides — the 2001 Stockholm Convention on Persistent Organic Pollutants — included an exemption for DDT for the use of malaria control until affordable substitutes could be found.[79]) Mass outdoor spraying of DDT was abandoned in poor countries subject to malaria, such as Sri Lanka, in the 1970s and 1980s, not because of government prohibitions, but because the DDT had lost its ability to kill the mosquitoes.[79] (Because of insects very short breeding cycle and large number of offspring, the most resistant insects that survive and pass on their genetic traits to their offspring replace the pesticide-slain insects relatively rapidly. Agricultural spraying of pesticides produces resistance to the pesticide in seven to ten years.[87])

I would go so far as to even say GP is wrong. The article describes how experiments show the mosquito's olfactory system appears to loose sensitivity to DEET after the first exposure. There is no supporting evidence that conclusively points to this being due to evolutionary change. A more appropriate characterization is simply that the insect's nervous system is being down-regulated in responsiveness to this particular chemical. In other words, the mosquito adapts by learning to ignore some noxious gunk in order to get a blood meal. If such is the case, the insect is simply showing that it can be conditioned with the right stimuli. This is neural-plasticity, not evolution.

Interestingly, not so long ago I read about evolution in humans, and how that is actually speeding up currently.

And that makes total sense to me, considering the huge changes we made to our environment over the past couple hundred years. Urbanisation, industrialisation - it requires different skills than farming.